The way oda is keeping things around shanks and Mihawk secretive, You know, it's possible that oda somehow makes shanks and Mihawk the final opponents of Luffy and Zoro.
Luffy never declared to surpass Roger. But he did say he will find a crew that can surpass shanks crew.
Zoro declared to surpass mihawk.
Maybe, just maybe Luffy didn't include himself when he said that.
Meaning maybe, just maybe, he meant, I will find people who can defeat your crew "by themselves"
Making Shanks a stepping stone for Zoro before facing the WSS Mihawk "supposedly higher".
I mean, who knows, maybe Luffy will sit on the sides, eating meat, and see Zoro beat the crap out of Shanks LOL. This makes him look like a more worthy king of pirates LOL.
Specially if oda made a call back to the dialog between Luffy and Zoro
Luffy: if you couldn't become the WSS, I would be in a dilimma
Which could make it an astonishing call back, where Luffy always had in his mind the idea of having a swordsman in his crew to beat Shanks (a swordsman)
Damn, Zoro fans would have some real orgasms doing that hahahah
Sanji faces Beckmann in the battle of cigarettes
And Luffy will have a meat contest with Lucky roo instead of fighting LOL